Diaphragm-type hydraulic accumulators



Nov; 11, 1969 E. HENRY-BIABAUD 3,477,473

DIAPHRAGM-TYPE HYDRAULIC ACCUMULATORS Filed June 19, 1967 FIG. I

FIG. 2 i 4 2 5 a /"ml A enxylhnn/f Jnoenfal 3 9 final United States Patent 3,477,473 DIAPHRAGM-TYPE HYDRAULIC ACCUMULATORS Edmond Henry-Biabaud, Paris, France, assignor to Societe Anonyme Andre Citroen, Paris, France Filed June 19, 1967, Ser. No. 646,842 Claims priority, applicgg'tgisFrance, July 21, 1966,

Int. Cl. r161 55/04 US. Cl. 138-30 4 Claims ABSTRACT OF THE DISCLOSURE A method of and means for securing a partition-forming diaphragm of elastomeric or like material, having its open edge clamped between the external casing and an inner plate pulled from the outside by means acting in combination with the inflation are already known and now in common use and not coverable by a patent, as they are described and illustrated in the French Patent No. 913,487.

Now various improvements have been brought to this arrangement, wherein an elastic plate is used.

According to these improvements, the edge of the partition-forming diaphragm is not only clamped by the pulling elfort of said plate during the mounting but also compressed by the internal pressure during the inflation and by the pressure prevailing in the accumulator when the latter is in actual service. This last-named pressure tends to urge the marginal portion of the diaphragm by causing the distortion of the elastic plate. Now this arrangement is attended by several drawbacks. Thus,

(1) The clamping force is not constant but subordinate to the internal pressure;

(2) The edge of the diaphragm is likely to become extruded when clamped between the casing and the clamping plate, even if very moderate localized clearances are provided between these two elements;

(3) If the clamped marginal portion of the diaphragm does not fill completely the gap provided between the casing and the inner plate, as this gap is subjected on the one side to the pressure existing in the accumulatorand on the other side to the atmospheric pressure, it will move due to the unavoidable variations in the internal pressure, this movement being likely to prove detrimental in the case of high and pulsatory pressure accumulators.

With the present invention the above-mentioned drawbacks are avoided.

It is the object of the present invention to provide means for fastening a diaphragm of the type set forth hereinabove, by clamping one edge thereof, which are characterized essentially in that the clamping plate provides between this plate, the inner wall of the accumulator and the edge of the diaphragm a free gap which is caused to communicate with the gaseous medium contained in the accumulator, the gaseous medium being isolated from the external atmosphere surrounding the accumulator by a gasket sealing the joint of the inflation plug.

Thus, a constant clamping of the diaphragm edge is obtained while enabling the internal pressure to act on both sides of the diaphragm edge, due to the use of a 3,477,473 Patented Nov. 11, 1969 rigid, non-tight plate. The clamping of the diaphragm edge is constant and adjustable according to the pull exerted on the plate, of which not one point is in contact with the casing.

The risks of extrusion or premature wear by fatigue are thus safely avoided and the accumulator is particularly capable of withstanding a wide range of pressures, even of pulsatory character.

In order to afford a clearer understanding of this invention and of the manner in which the same may be carried out in practice, a typical form of embodiment thereof will now be described by way of example with reference to the accompanying drawing, in which:

FIGURE 1 illustrates diagrammatically a diaphragmtype hydraulic accumulator constructed according to the teachings of this invention.

FIG. 2 is a partial cross-section showing a modification.

In the drawing the reference numeral 1 designates the casing of a hydraulic accumulator provided with a connecting union 2 and divided by a diaphragm 5 into two compartments 3 and 4 one containing a. gaseous medium under pressure and the other a liquid. This diaphragm 5 made of suitable elastomer comprises a lip 6 and a lateral portion 7 contacting the inner wall of the accumulator casing 1. The assembly comprising the accumulator casing 1, the connecting union 2 and the diaphragm 5 is advantageously of revolution about an axis 8; however, it will readily occur to anyone conversant with the art that the accumulator casing 1 may consist of two half-shells assembled for example by screwing, according to manufacturing requirements.

According to a specific form of embodiment of the present invention, a clamping plate 10 secured to the internal surface of the accumulator casing 1, for example, by means of a screw plug 13 provided with a nut 17, reserves between the clamping plate, the internal wall of the accumulator casing and the edge of said diaphragm a free gap 12 communicating with compartment 3 through a hole 18 formed in said clamping plate 10. This plate 10 comprises means for pressing the diaphragm against the casing, for example in the form of shoulders such as 19 and 22 (see FIG. 1) or a rounded edge 23 engaging a corresponding groove 24 formed in the diaphragm (FIG. 2).

As a result, the pressure prevailing in the space 12 and on the diaphragm edge 6 is constantly equal to the pressure of the gaseous medium in compartment 3 and to that prevailing in the other, liquid-filled compartment 4. Moreover, the clamping plate '10 comprises cylindrical portions 20 and 21 which cannot be distorted by the pressure prevailing in the accumulator. These cylindrical portions clamp the edge 6 with a constant torce resulting from the tractive effort exerted by the fastening member 13, irrespective of the pressure prevailing in the accumulator 1.

Finally, it will be noted that the member 13 can be used as an inflation plug for introducing a gas into the upper compartment 3. In this case a gasket 14 seals the joint between this gas-filled compartment and the atmospheric air surrounding the accumulator.

The above-described form of embodiment of the present invention should not be construed as limiting same since lower part the edge of said diaphragm to said casing, a member used as an inflation plug securing said plate at its upper part to said casing, said upper part of said c1amping plate having a shape providing, when secured, between said plate, the upper part of the internal wall of said casing and the edge of said diaphragm a free constant gap communicating through said clamping plate with said gaseous medium in said casing to equalize the pressures prevailing on said edge and on said lateral portion of said diaphragm so as to avoid movements of the diaphragm edge, said member permitting adjusting of the pull on said clamping plate which does not come in contact with said wall, and a gasket sealing the joint of said member to obtain gas tightness between said gaseous medium and the atmosphere surrounding said casing.

2. Diaphragm type hydraulic accumulator according to claim 1, wherein a hole is provided in the upper part of said clamping plate for establishing communication between said free gap and said gaseous medium.

3. Diaphragm type hydraulical accumulator according to claim 1, wherein said clamping plate comprises-in its lateral part a shoulder and a cylindrical portion contacting the edge of said diaphragm in the vicinity of said shoulder.

4. Diaphragm type hydraulic accumulator according to claim 1, wherein said diaphragm has a groove and said clamping plate comprises a rounded edge engaged in said groove and a cylindrical portion contacting the edge of said diaphragm.

References Cited UNITED STATES PATENTS 2,676,605 4/1954 Meredew 138-30 XR 3,038,501 6/1962 Greer l38--3O 3,195,578 7/1965 Mercier 138-30 3,208,646 9/1965 Wessenger 138-30 XR FOREIGN PATENTS 213,371 3/1958 Australia. 597,550 5/1960 Canada.

ROBERT R. MACKEY, Primary Examiner 

